Power harvesting in reader devices

ABSTRACT

Aspects of the subject disclosure provide a reader device for processing payment cards. The reader device is configured to harvest power from received audio signals, for example, from analog signals received on an audio bus, such as a standard 3.5 mm audio channel. In some implementations, a reader of the current technology includes a microcontroller configured to perform operations including receiving an audio signal from the host via the audio bus, analyzing the audio signal to determine when a voltage of the audio signal is negative and providing a reference signal to the power module, wherein the reference signal indicates time periods in which synchronous rectification is to be performed by the power module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/914,762, entitled “POWER HARVESTING IN READER DEVICES”, filed on Dec. 11, 2013, and which is hereby expressly incorporated herein by reference in its entirety.

BACKGROUND

The ubiquity of headphone ports makes them an attractive option for use as communication channels for attachable hardware devices. For example, 3.5 mm audio ports are standard on many electronic devices and in particular, mobile devices such as smart phones and tablet computers. Such audio ports can be used to provide communication between a host device and a hardware attachment, such as an attachable card reader (e.g., a “reader”) used for reading information from a payment card.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain features of the subject technology are set forth in the appended claims. However, the accompanying drawings, which are included to provide further understanding, illustrate disclosed aspects and together with the description serve to explain the principles of the subject technology. In the drawings:

FIG. 1 illustrates a conceptual block diagram of hardware components used to facilitate power harvesting from an audio signal;

FIG. 2 illustrates a conceptual block diagram of the coupling between an audio bus and a power module, according to some implementations of the subject technology;

FIG. 3 illustrates an example process in which DC power is harvested from an audio signal received by a reader;

FIG. 4 illustrates an example reader, including an audio plug, according to some implementations; and

FIG. 5 depicts a conceptual environment in which a reader of the subject technology can be used to facilitate a financial transaction between a buyer and a merchant.

DETAILED DESCRIPTION

The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the technology can be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description, which includes specific details for the purpose of providing a more thorough understanding of the subject technology. However, it will be clear that the subject technology is not limited to the specific details set forth herein and may be practiced without these specific details. In some instances, structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology.

Due to limitations in using audio ports for data transport, some conventional readers are restricted to unidirectional communication and are only capable of sending signals to a host mobile device (and not receiving them). As a consequence, audio signals that may be transmitted on the audio bus (e.g., via left and/or right audio channels), are ignored or otherwise unused. Furthermore, while in some conventional reader implementations, the reader is configured to draw power from the microphone channel (which is typically powered for the purpose of driving power to a microphone amplifier), conventional reader devices typically have no other source of power. It would be advantageous to deliver an increased amount of power to the reader during the course of normal reader operation and without requiring separate charging to be performed by a user.

Systems and methods in accordance with various aspects of the present disclosure overcome one or more of the above-referenced and other deficiencies in conventional reader powering. In particular, aspects of the technology provide solutions for harvesting power from an audio bus to produce a DC output from audio signals received on left and/or right audio channels, included in standard 3.5 mm audio channels. As discussed in further detail below, power harvested from audio signaling can be used to directly power component parts of a reader, and in some implementations, can be stored for later use, for example, using a power storage device such as a rechargeable battery.

Implementations of the subject technology provide methods and systems for harvesting DC power from audio signals received by a reader over an audio channel that is coupled to a standard 3.5 mm audio port or plug. In certain aspects, one or more transistors, such as field effect transistors (FETs), can be used to perform synchronous rectification on received audio signals. Synchronous rectification can be used to rectify the full wave of a received audio signal, including negative voltage components. By using synchronous rectification, power conversion (e.g., into a DC output) can be accomplished more efficiently as compared to conventional diode rectification techniques, which incur a greater power loss due to the relatively high voltage differential required for diode biasing.

As discussed in further detail below, power harvesting from audio signals is performed in a manner wherein switching of a power module (e.g., transistors of a synchronous rectification circuit), is controlled to correspond with variations in the received signal. For example, by detecting a frequency of the incoming audio signal, a microcontroller can predict time periods in which a voltage of the received signal is negative. Accordingly, the microcontroller can provide signaling (e.g., a “reference signal”) indicating when synchronous rectification should be performed.

FIG. 1 illustrates a conceptual block diagram of example hardware components of a reader 100 configured to harvest power from received audio signals, according to some aspects. Reader 100 includes microcontroller 110, memory 120, digital-to-analog converter (DAC) 130, analog-to-digital converter (ADC) 140, power module 150, power storage device 160, and card reader 170.

As illustrated, microcontroller 110 is coupled to memory 120, DAC 130 and ADC 140. Additionally, microcontroller 110 is communicatively coupled to power module 150, via reference channel 121 and DC output line 122. Microcontroller 110 is further coupled to power storage device 160, via DC output line 123, as well as to card reader 170, via ADC 140. As further illustrated in the example of FIG. 1, reader 100 is coupled to an audio bus comprising microphone channel 105 and audio channel 115. Specifically, DAC 130 is coupled to microphone channel 105, configured to transmission of signaling to a host device (e.g., as an output from reader 100), whereas ADC 140 is coupled to audio channel 115, for reception of audio signaling from the host device.

Reader 100 can be implemented using various other hardware components and/or configurations, and is not limited to the architecture depicted in the example of FIG. 1. For example, microcontroller 110 can be implemented using a general-purpose processor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device (PLD), a controller, a state machine, gated logic, discrete hardware components, or a combination of the foregoing.

Additionally, various types of memory can be utilized in place of, or in addition to, memory 120. Similarly, one or more sequences of instructions may be stored as firmware on a ROM within microcontroller 110. One or more sequences of instructions can also be software stored and read from another storage medium, such as the flash memory array, or received from a host device (e.g., a mobile device such as a smart phone or tablet computing device) via a host interface, such as audio channel 115. ROM, storage mediums, and flash memory arrays represent examples of machine or computer readable media storing instructions/code executable by microcontroller 110. Machine or computer readable media may generally refer to any medium or media used to provide instructions to microcontroller 110, including both volatile media, such as dynamic memory used for storage media or for buffers within microcontroller 110, and non-volatile media, such as electronic media, optical media, and magnetic media.

Taken together, microphone channel 105 and audio channel 115 can form a portion of an audio bus incorporating a standard 3.5 mm audio plug (not shown). In some implementations, audio channel 115 can include multiple audio channels, such as a left-speaker channel and a right-speaker channel of a 3.5 mm headphone port.

Audio signaling received on audio channel 115 is provided to power module 150 and microcontroller 110. The audio signaling can be provided directly to a pin of microcontroller 110, in an embodiment in which microcontroller 110 has an audio analysis component (e.g., a component to analyze positive and negative voltages, etc.), or can be provided indirectly to a pin of microcontroller 110 via a transistor buffer (not shown) for lifting the audio signal above ground. Thus, the audio signaling received by microcontroller 110 can be analyzed and used to provide a reference signal to power module 150 (e.g., via reference channel 121), so that parameters of power module 150 can be altered in order to rectify the received audio signals in an efficient manner to produce a DC output from the received audio waveform. In this way, microcontroller 110 “listens” to the received AC waveform, and controls power module 150 (e.g., using a reference signal) in order to perform synchronous rectification on the received audio signals at proper time intervals.

Although synchronous rectification performed by power module 150 can be achieved using different circuit implementations, in certain aspects one or more FETs can be used, as discussed in further detail with respect to FIG. 2, below. Transistor based synchronous rectification techniques provide advantages over conventional diode rectification by mitigating the relatively high voltage drops experienced when transferring power over a typical diode p-n junction.

Because transistor biasing can be affected by a ground state voltage of microcontroller 110, in certain aspects, changes in the (floating) ground state voltage of microcontroller 110 can be self-timed (e.g., by microcontroller 110), for example, based on the received audio signal/transistor biasing. Thus, in addition to controlling synchronous rectification of power module 150, microcontroller 110 is also configurable to alter its ground state voltage based on audio signaling received via audio channel 115. Further, because transistor biasing can be affected by a ground state voltage of microcontroller 110, in one embodiment power module 150 is at least partially electrically isolated (by, e.g., the use of an optical interconnect on reference channel 121, etc.) from microcontroller 110, to help ensure the proper operation of power module 150.

In certain aspects, after received audio signaling is rectified the resulting DC power is outputted from power module 150. Although the DC power can be used to provide power to any component of reader 100, in some implementations the DC power is provided directly to microcontroller 110, e.g., via DC output line 122.

In other implementations, the DC power output by power module 150 is provided to power storage device 160 (via DC output line 119), and stored for future use by reader 100. For example, charge stored by power storage device 160 can later be provided to microcontroller 110 via DC output line 123. Power storage device 160 can include any type of charge storage device or material, such as a capacitor or inductive network; however, in some implementations, power storage device 160 includes a rechargeable battery for storing charge even when all external power to reader 100 is cut off.

Additionally, although in the example of FIG. 1 power storage device 160 is shown to be coupled solely to power module 150 and microcontroller 110, it is understood that in other implementations power storage device can be coupled to additional/different components of reader 100. By way of example, power storage device can be configured to provide DC power to card reader 170 to facilitate reading of a payment card used in a financial transaction.

DC output line 123 can be used to carry signaling between power storage device 160 and microcontroller 110. Using DC output line 123, microcontroller 110 can be configured to detect a power level of power storage device 160, for example, to determine if/when power storage device 160 is in a low power state. Determinations of a low power state of power storage device 160 may be made if/when an amount of charge stored by power storage device 160 is determined to be below a predetermined threshold. In some implementations, the detection of a low power state of power storage device 160 can be used to determine whether power output by power module 150 should be used to charge power storage device 160, or delivered directly to one or more other components of reader 100.

A more detailed example of a power module, as well as the power module's connection to an audio bus, is illustrated by the conceptual block diagram of circuit 200 in FIG. 2. As depicted, circuit 200 includes an audio bus 210, comprising microphone channel 215, ground 225, right audio channel 230, and left audio channel 235. Circuit 200 further depicts that power module 150 is coupled to audio bus 210. Power module 150 includes synchronous rectification circuit 205 having DC output line 119 for carrying DC output power. Synchronous rectification circuit 205 is also coupled to reference channel 121, e.g., to receive a reference signal from a microcontroller (e.g., microcontroller 110), not shown. As discussed above, the reference signal provided by microcontroller 110 can be used to indicate information about voltage levels and timing of a received audio signal necessary for properly biasing one or more transistors of synchronous rectification circuit 205. In certain aspects, power module 150 may be implemented using FET transistors, for example in a ‘H’ bridge configuration; however, it is understood that various synchronization circuit configurations can be implemented without departing from the scope of the subject technology.

As discussed above, DC output line 119 can be used to provide DC power to any portion or component of a reader, including either directly to a microcontroller, or a power storage device, such as a rechargeable battery.

An example, of steps of a process for engaging in synchronous rectification of an audio signal is illustrated in process 300 depicted in FIG. 3. Process 300 begins with step 302 in which an audio signal is received from a host device, e.g., via an audio bus. As used herein, a host device can include any device configured for transmitting audio signals and that may be communicatively coupled to the reader via an audio channel. By way of example, a host can be any device with a headphone port configured to accept insertion of a standard 3.5 mm audio plug and may include, but is not limited to: smart phones, tablet computers, personal computers, mobile music or MP3 players and/or portable gaming devices, etc.

In certain aspects the audio signal from the host device is received on a left and/or right audio channel of an audio bus of the 3.5 mm audio plug. The received audio signal can be provided by the host device for the purpose of transmitting data, e.g., to the reader. Alternatively, in some implementations the received audio signal may be transmitted for the purpose of providing audio signaling from which DC power can be harvested.

In step 304, the received audio signal is analyzed to determine when a voltage of the audio signal is, or will be, negative.

For synchronous biasing of the audio signal to be effective, variations in transistor biasing need to correspond with fluctuations in the voltage of the audio signal. Thus, analysis of the audio signal (e.g., by a microcontroller or processor) can be used to determine when biasing parameters (e.g., for biasing one or more transistors of a synchronous rectification circuit) should be changed.

As discussed above, a ground state voltage of the microcontroller may also need to be changed in order to perform proper transistor biasing. Thus, analysis of the received audio signal can be used not only determine how to regulate transistor biasing, but also for regulating the floating ground state voltage of the microcontroller.

In step 306 a reference signal is provided (e.g., by a microcontroller) to a power module, wherein the reference signal indicates time periods in which synchronous rectification is to be performed by the power module. The reference signal can include signaling for directly biasing one or more transistors (e.g., FETs) of the power module. Alternatively, the reference signal can convey various signal properties (e.g., frequency and/or voltage information) that are interpreted by the power module to determine how synchronous rectification is to be performed.

Subsequently, in optional step 308, DC power is output by the power module and provided to a power storage device, (e.g., power storage device 160 discussed above). Alternatively, DC power outputted by the power module can be provided to another component of the reader, such as a card reader configured for reading an integrated circuit (IC) type payment card.

The ability to increase an amount of power delivered to the reader can provide several advantages. For example, by harvesting power from received audio signals, a rechargeable storage device (e.g., power storage device 160) can be charged/researched-prolonging the useful life of the reader device. Additionally, by increasing an amount of power that is deliverable to the reader, an increased number of processing tasks may be accomplished by the reader, without the need for increasing a form factor of the reader to accommodate an enlarged power storage device.

In certain aspects, the delivery of audio signals that are harvested to produce DC power outputs can be triggered in response to a request issued by the reader device. For example, upon sensing a low power state of a power storage device, the microcontroller can request an audio signal (e.g., from a host device), so that the audio signal can harvested (i.e., rectified), to provide DC power necessary to recharge the power storage device.

Ultimately, any increased functionality and/or life provided to the reader as a result of power harvesting will enable the reader to perform its function of reading payment card information to facilitate financial transactions.

FIG. 4 illustrates an external view of an example reader 400 according to some embodiments of the technology. Reader 400 includes housing 410 having card slot 412. As illustrated, housing 410 is coupled to audio plug 420 (e.g., a 3.5 mm audio plug).

Housing 410 contains the hardware modules, components and circuitry of reader 400, as illustrated with respect to the example of FIGS. 1 and 2. Additionally, housing 410 is designed to physically receive a payment card via slot 412. By way of example, a payment card containing a magnetic stripe may be swiped through slot 412 in order to provide payment information to reader 400. Passage of a magnetic stripe of the payment card past a read head contained in housing 410 (e.g., as part of card reader 170), can enable payment information to be received via the read head. The resulting signal provided by the read head is typically an analog signal that must be digitized e.g., using ADC 140, before the payment information is provided to microcontroller 110.

Different types of information can be read from a magnetic stripe, depending on implementation. For example, user and payment card account information can be read from track 1 and track 2 of the magnetic stripe, respectively. However, in other implementations, any track (or combination of tracks) may be read from the magnetic stripe, including any combination, or all of tracks 1, 2 and 3.

In another example, reader 400 may be configured to accept integrated circuit (“IC”) cards, using slot 412. As such, slot 412 can be configured as a “dip slot” for the insertion of at least a portion of a payment card, including an integrated circuit or chip. As such, it is understood that the reader can be configured to receive other types of payment cards, and accordingly can contain additional or different hardware and/or software modules than those described above with respect to FIG. 1. By way of a non-limiting example, reader 400 can be configured to accept/read various forms of payment cards, such as those conforming to the Europay, MasterCard, and Visa (EMV) standard.

As illustrated, housing 410 is physically and communicatively coupled to audio plug 420, which can be removably inserted into a headphone port of a host device, such as a smart phone, tablet device, or the like. As discussed above with respect to FIGS. 1 and 2, audio plug 420 forms part of an audio bus that includes left and right speaker channels, a microphone channel and a ground connection. Once audio plug 420 is inserted into the headphone port of a host device, such as a smart phone, audio signaling can be received by the reader e.g., via the left/right speaker channels and microphone channel, using the methods and systems discussed above.

After successful communication has been established between the reader and its host, the reader can be used to facilitate a payment transaction, for example between a merchant and a buyer using a magnetic payment card.

FIG. 5 depicts a conceptual environment in which a reader of the subject technology can be used to facilitate a financial transaction between a buyer and a merchant. Although the diagrams depict components as functionally separate, such depiction is merely for illustrative purposes. It will be apparent that the components portrayed in this figure can be arbitrarily combined or divided into separate software, firmware and/or hardware components. Furthermore, it will also be apparent that such components, regardless of how they are combined or divided, can execute on the same host or multiple hosts, and wherein multiple hosts can be connected by one or more networks.

In the example of FIG. 5, the system includes a mobile device 500, a reader 501 connected to mobile device 500, a decoding engine 510, a user interaction engine 520, and a transaction engine 530, all running on mobile device 500. Additionally, the system may also include one or more of a user database 540, a product or service database 550, and a transaction database 560, all coupled to the transaction engine 530.

As used herein, the term engine refers to software, firmware, hardware, and/or other components used to effectuate a purpose. The engine will typically include software instructions that are stored in non-transitory computer-readable memory (also referred to as secondary memory). When the software instructions are executed, at least a subset of the software instructions is loaded into memory (also referred to as primary memory) by a processor. The processor then executes the software instructions in memory. The processor may be a shared processor, a dedicated processor, or a combination of shared or dedicated processors. A typical program will include calls to hardware components (such as I/O devices), which typically requires the execution of drivers. The drivers may or may not be considered part of the engine, but the distinction is not critical.

As used herein, the term database is used broadly to include any known or convenient means for storing data, whether centralized or distributed, relational or otherwise.

In the example of FIG. 5, mobile device 500 to which reader 501 is connected can be, but is not limited to, a cell phone, such as Apple's iPhone, other portable electronic devices, such as Apple's iPod Touches, Apple's iPads, and mobile devices based on Google's Android operating system and any other portable electronic device that includes software, firmware, hardware, or any combination capable of at least receiving the signal, decoding if needed, exchanging information with a transaction server to verify the buyer and/or seller's account information, conducting the transaction, and generating a receipt. Typical components of mobile device 500 can include but are not limited to persistent memories like flash ROM, random access memory like SRAM, a camera, a battery, LCD driver, a display, a cellular antenna, a speaker, a Bluetooth circuit, and WiFi circuitry, where the persistent memory may contain programs, applications, and/or an operating system for the mobile device.

In some implementations, a system is provided with transaction engine 530 running on mobile device 500. In response to a financial transaction between a buyer and a seller, mobile device 500 accepts information selected including but not limited to information from financial transaction or information pertaining to financial transaction card used by the buyer in the transaction. Additionally, a financial transaction device can be utilized. Non-limiting examples of financial transaction devices include but are not limited to a wristband, RFID chip, cell phone, biometric marker and the like. At least a portion of this information is communicated to a third party financial institution or payment network to authorize the transaction.

Payment confirmation can be made with a communication channel of the buyer's choice. As non-limiting examples, confirmation of payment can be an electronic notification in the form selected from at least one of, email, SMS message, tweet (message delivered via Twitter), instant message, communication within a social network and the like. In response to the transaction, a confirmation is made that the buyer is authorized to use the financial transaction card. In certain implementations, a confirmation can be provided that indicates a sufficiency of funds available to the buyer.

In the example of FIG. 5, reader 501 is configured to read data encoded in a magnetic strip of a card being swiped by a buyer and send a signal that corresponds to the data read to mobile device 500. However, as discussed above, reader 501 may be configured to receive various payment card types, including but not limited to IC cards that can be provided to reader 501 using a dip slot.

The size of reader 501 can be miniaturized to be portable for connection with mobile device 500. For example, the size of reader 501 can be miniaturized to an overall length of less than 1.5″. In addition, the reader 501 is also designed to reliably read the card with minimum error via a single swipe by counteracting vendor specific filtering done by mobile device 500. Note that this broad overview is meant to be non-limiting as components to this process are represented in different embodiments.

Many of the above-described features and applications are implemented as software processes that are specified as a set of instructions recorded on a computer readable storage medium (also referred to as computer readable medium). When these instructions are executed by one or more processing unit(s) (e.g., one or more processors, cores of processors, or other processing units), they cause the processing unit(s) to perform the actions indicated in the instructions. Examples of computer readable media include, but are not limited to, flash drives, RAM chips, hard drives, EPROMs, etc. The computer readable media does not include carrier waves and electronic signals passing wirelessly or over wired connections.

In this specification, the term “software” is meant to include firmware residing in read-only memory or applications stored in magnetic storage, which can be read into memory for processing by a processor. Also, in some implementations, multiple software aspects of the subject disclosure can be implemented as sub-parts of a larger program while remaining distinct software aspects of the subject disclosure. In some implementations, multiple software aspects can also be implemented as separate programs. Finally, any combination of separate programs that together implement a software aspect described here is within the scope of the subject disclosure. In some implementations, the software programs, when installed to operate on one or more electronic systems, define one or more specific machine implementations that execute and perform the operations of the software programs.

A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

These functions described above can be implemented in digital electronic circuitry, in computer software, firmware or hardware. The techniques can be implemented using one or more computer program products. Programmable processors and computers can be included in or packaged as mobile devices. The processes and logic flows can be performed by one or more programmable processors and by one or more programmable logic circuitry. General and special purpose computing devices and storage devices can be interconnected through communication networks.

Some implementations include electronic components, such as microprocessors, storage and memory that store computer program instructions in a machine-readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic and/or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra density optical discs, any other optical or magnetic media. The computer-readable media can store a computer program executable by at least one processing unit, such as a microcontroller, and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, such as is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter.

While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some implementations are performed by one or more integrated circuits, such as application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). In some implementations, such integrated circuits execute instructions that are stored on the circuit itself.

As used in this specification and any claims of this application, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. As used in this specification and any claims of this application, the terms “computer readable medium” and “computer readable media” are entirely restricted to tangible, physical objects that store information in a form readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals.

Embodiments of the subject matter described in this specification can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks).

The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. In some embodiments, a server transmits data (e.g., an HTML page) to a client device (e.g., for purposes of displaying data to and receiving user input from a user interacting with the client device). Data generated at the client device (e.g., a result of the user interaction) can be received from the client device at the server.

It is understood that any specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged, or that all illustrated steps be performed. Some of the steps may be performed simultaneously. For example, in certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. Pronouns in the masculine (e.g., his) include the feminine and neuter gender (e.g., her and its) and vice versa. Headings and subheadings, if any, are used for convenience only and do not limit the subject disclosure.

A phrase such as an “aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. A phrase such as an aspect may refer to one or more aspects and vice versa. A phrase such as a “configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A phrase such as a configuration may refer to one or more configurations and vice versa.

The word “exemplary” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs.

All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. 

What is claimed is:
 1. A reader for receiving payment card information to facilitate a financial transaction, the reader comprising: an audio bus coupled to an audio plug, wherein the audio plug is configured for coupling with a headphone port of a host device to provide communication between the reader and the host device during a financial transaction in which the reader receives payment card information from a payment card and provides the payment card information to the host device via the audio plug; a power module coupled to the audio bus, wherein the power module is configured to perform synchronous rectification on audio signals received via the audio bus using one or more transistors of the power module to provide power to the reader during the financial transaction; and a microcontroller coupled to the audio bus and the power module, wherein the microcontroller is configured to perform operations for: receiving an audio signal from the host device via the audio bus; analyzing the audio signal to determine when a voltage of the audio signal is negative; and providing a control signal to the power module based on the analysis of the audio signal, wherein the control signal indicates when synchronous rectification is to be performed by the power module.
 2. The reader of claim 1, wherein the power module is configured to output DC power to the microcontroller.
 3. The reader of claim 1, further comprising: a power storage device coupled to the microcontroller and the power module, wherein the power module is configured to output DC power to the power storage device.
 4. A method for powering a reader for receiving payment card information to facilitate a financial transaction, the method comprising: receiving, by a power module, an audio signal transmitted by a host via an audio bus; analyzing the audio signal, using a microcontroller, to determine when a voltage of the audio signal is negative; and providing a control signal from the microcontroller to the power module based on the analysis of the audio signal, wherein the control signal indicates time periods in which synchronous rectification is to be performed on the audio signal using one or more transistors of the power module.
 5. The method of claim 4, wherein the power module is configured to output DC power to the microcontroller.
 6. The method of claim 4, wherein the power module is configured to output DC power to a power storage device coupled to the power module and the microcontroller.
 7. The method of claim 4, wherein the microcontroller is configured to detect a power level of a power storage device.
 8. The method of claim 7, further comprising: detecting, by the microcontroller, a low power state of the power storage device based on the power level of the power storage device; and causing the power module to supply power to the power storage device, in response to the low power state.
 9. The method of claim 4, further comprising: adjusting a ground state voltage of the microcontroller based on the audio signal.
 10. The method of claim 4, further comprising: receiving power at a card reader from a power storage device; reading, using the card reader, payment information from a payment card; and providing the payment information to the microcontroller.
 11. A non-transitory computer-readable storage medium comprising instructions stored therein, which when executed by one or more processors, cause the processors to perform operations comprising: analyzing an audio signal, using a microcontroller, to determine when a voltage of the audio signal is negative; and providing a control signal from the microcontroller to a power module based on the analysis of the audio signal, wherein the control signal indicates time periods in which synchronous rectification is to be performed using one or more transistors of the power module.
 12. The non-transitory computer-readable storage medium of claim 11, wherein the power module is configured to output DC power to the microcontroller.
 13. The non-transitory computer-readable storage medium of claim 11, wherein the power module is configured to output DC power to a power storage device coupled to the power module and the microcontroller.
 14. The non-transitory computer-readable storage medium of claim 11, wherein the microcontroller is configured to detect a power level of a power storage device.
 15. The non-transitory computer-readable storage medium of claim 14, wherein the microcontroller is further configured to perform operations comprising: detecting a low power state of the power storage device based on the power level; and causing the power module to supply power to the power storage device, in response to the low power state.
 16. The non-transitory computer-readable storage medium of claim 11, the instructions further comprising: adjusting a ground state voltage of the microcontroller based on the audio signal.
 17. The non-transitory computer-readable storage medium of claim 11, the instructions further comprising: receiving power at a card reader from a power storage device; reading, using the card reader, payment information from a payment card; and providing the payment information to the microcontroller.
 18. The non-transitory computer-readable storage medium of claim 17, wherein the payment card comprises a magnetic stripe payment card.
 19. The non-transitory computer-readable storage medium of claim 17, wherein the payment card comprises an integrated circuit (IC) type payment card.
 20. The non-transitory computer-readable storage medium of claim 19, wherein the payment card comprises data conforming to a Europay, MasterCard, and Visa (EMV) standard. 